how to do newlines and how to submit when editing text

I just happened to be reading Hacker News and saw this:
"In text boxes in some applications, enter submits the entered text, and
ctrl-enter forces a newline (not at my computer, but I think Slack does
this). In others, it's the other way around"

and thought that stuff has caught me before, I seem to remember there is
some guideline on pressing enter should submit, but is there a guideline in
any accessibility standard on how the user should be able to do a new line
in entering text - and if so which standard is that in?

Thanks,
Bryan Rasmussen